Armature hold-down latch for electrical relays



R. c. Hess 2,916,677

ARMATURE HOLD-DOWN LATCH FOR ELECTRICAL RELAYS Dec. 8, 1959 Filed Feb. 21, 195'? fe C w w c uw 5w f Jpn JW F l0 4 /AHr//ff/f f /lrnf/r/r/4 I n f :ad a .JM Jy., u 7 m .m 5 A@ E, an@ u M9 5^ 2 8 9 4N .o d .0

am M Z I i: J M JN United States Patent ARMATURE HOLD-DOWN LATCH FOR y l ELECTRICAL RELAYS Application February 21, 1957, serial No. 641,710

s Claims. (ci. 3171-187) My invention relates to electrical relays, and particularly to electrical relays of the plug-in type, suitable for use in applications where the relays may be subjected to severe vibration, such, for example, as railway signaling applications. More particularly, my present invention relates to a means for preventing the armatures of relays of the type described from vibrating sufficiently in their deenergized position to cause improper operation of the relay contacts.

Certain types of relays which are used in railway signaling applications have a relatively large tractive armature operatively connected through suitable linkage with movable contact lingers which cooperate with fixed front and back contact lingers to close the front or back contacts of the relay according as the relay is energized or deenergized. In many instances, the relays are mounted in instrument houses along the railroad right-of-way, and as a consequence when a train passes, the relays are subjected to severe vibration. Two methods of supporting relays are commonly employed. In the one method, the relays are mounted on shelves, and with this type of mounting, the adverse elects of vibration can readily be overcome by inserting between the relays and the shelves shock absorbing mountings. In the other method, the relays are plugged into mounting bases, mounted on relatively large frames and are securely locked in place. With this latter method, since the relays are in effect rigidly connected to the frame, any vibration to which the frames are subjected is transmitted to the relay. It is impractical to shock mount the frames, and accordingly it becomes desirable to so construct the relays that vibration will not adversely affect the contact operation of the relays, particularly when the armatures of the relays are in their deenergized positions.

In previous relays, springs or permanent magnets, which exert a downward force on the relay armature, have been employed. Either of these means adversely aiects the calibration values of the relay, and one object of my present invention is to provide a latching means which can be employed to hold a relay armature in its deenergized position without materially affecting the calibration values of the relay. i

A further object of my invention is to provide a latching means which will become automatically unlatched by energization of the relay with current of either polarity.

`Other objects and characteristic features of my invention will become apparent as the description proceeds.

In accordance with my invention, I provide the relay armature with a latch which is pivotally attached at one end to the larmature and which cooperates at its other end with an angled step formed in a bracket that extends downwardly past the free end of the armature to a point underneath the armature and serves as a back stop to limit the movement of the armature away from the relay pole pieces when the relay becomes deenergized. The

latch is constructed of magnetizable material and is disposed at such an angle with respect to the armature that 7 any movement of the armature away from its released position without first lifting the latching will cause the Patented Dec. 8, 1959 end of the latchl to wedge against the riser of the step in the back stop bracket and thus effectively limit the arma-4 ture movement to a relatively small amount which is insullcient to open the back contacts of the relay, However, when the relay becomes energized, the latch being of magnetizable material will be attracted by the same ilu'x which tends to move the armature to its attracted position, and since the latch has a much smaller mass than the armature, its free end will be lifted clear of the step in the back stop before the armature starts to move. As -a result, as soon as the llux builds up to a suiiicient value to start the movement of the armature, the latch willhave little, if any, effect on the further movement of the armature. It follows that the latch will have very little, if any, effect on the relay current required to pick up the relay armature, but will act to effectively prevent undesirable movement of the armature in its deenergized position due to vibration.

I shall describe one form of relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings,

Fig. l is a side view partly in section and partly in ele'- vation showing a relay, the armature of which is provided with one form of latch embodying my invention.

Fig. 2 `is an enlarged view of the armature latch in the latching position which it occupies when the relay is deenergized.

Fig. 3 is an enlarged View of the armature latch in the unlatched position which it assumes when the relay is energized.

Fig. 4 is a right-hand end view of Fig. 2.

Similar reference characters refer to similar parts in each of the several views.

Referring to the drawings, the relay comprises a frame member 1 ofsuitable nonmagnetizable material such as die cast aluminum. This frame member is provided with a vertical portion 1a and an integral forwardly extending portion 1-b. The relay is intended to be plugged into a suitable mounting base, not shown, and a handle 1e is secured to the front of portion 1b to facilitate plugging the relay into and removing it from the mounting base. Pole pieces 2 and 2a of suitable magnetizable material, such as'silicon steel, are secured within the portion 1b, and the upper ends of these pole pieces are bridged by a magnetizable backstrap 3 surrounded intermediate its ends by an energizing coil 4. The backstrap 3 is secured in place by bolts 3b passing through holes provided in the backstrap and screwed into threaded holes provided in frame member 1.

The coil 4 Iis provided with two contact prongs 4a, only one of which is shown. These contact prongs are intended to cooperate with suitable female contact members provided in the mounting base when the relay occupies its pluggedin position and serve as a convenient means for supplying energizing current to the coil 4.

Pivotally secured to the frame member 1 by leaf springs 5c and 5d is a tractive armature 5 movable to-l ward and away from the pole pieces 2 and 2a between an energized and a deenergized position. Securedv to the armature 5 by a securing block 5a is a contact actuator drive Wire 6. 'Ilhe contact actuator drive wire is in turn secured to a contact actuating member 7 made of suitable insulating material. Contact actuating mem' ber 7 is provided with a plurality of pins 7a for engaging a plurality of movable contact members 8.

Secured to the relay in` a position to cooperate with the movable contact members 8 are a plurality of fixed front and back contact members 9. Each of the contact 0 members 8 and 9 is secured in the vertical portion of the frame member and has its rear end extending beyond a portion of the frame so as to form prongs similar to the prong 4a. These prongs likewise cooperate with female receptacles provided in a mounting base (not shown) when` the relay is, in its plugged-in position. Located between` the contact actuator 7" and the drive wire' securing block Sir is a pressure spring 10 for holding the' drive wire 6 under a speciiied amount of tension.

A latch supporting member 11, provided with two downwardly extending portions 11a (see Fig. 4'), is secured as by rivets to the underside of the armature adjacent its free end. A flat rectangular latch13`made` of magnetizable material, such as low residual steel, is providedI at one end with an eye 13m (see Fig. 4), which is pivotally mounted on a pin 14. Pin 14 extends through theeye 13d of the latch and through holes 11b provided ineach of the downwardly extending portions of the latch supporting member 11 and is held in place by spreading the split ends on each end of the pin and soldering one end of the pin to the latch supporting member.

A thiny flat T-shaped latch stop member 12 made of n'onmagnetizable material is secured between the latch supporting. member and the armature. The leg of the latch stop member extends a short distance beyond the end' of the armature and restricts upward movement of the latch (see Fig. 3). A substantially U-shaped armature stop 15 made of nonmagnetic material or material of relatively low permeability is secured to the pole piece 2 by means of bolts 17 passing through holes provided in each of two laterally extending lugs 15d disposed at right angles to the leg 15e and forming a part of the armature stop 15. The bolts are prevented from turning by a lock washer 18.

The other leg 15]c of the armature stop 15 is` somewhat longer than the legs by which the armature stop is secured to the pole piece and extends away from; the leg 15e at an acute angle and ends beneath the armature. When the relay is deenergized this leg acts as a stop to position the armature in a predetermined position to which it moves by gravity or spring tension.

An angled step 15a is provided at the top of the leg 15e of the armature stop between the two lugs 15d,- and this step cooperates with the free end of the latch 13. The parts are so proportioned that when the relay isdeenergized the free end of the latch 13 will rest on the tread of the step relatively close to the riser of the step. The parts are further so proportioned that when-the latch is resting on the tread, it will be disposed at an angleof slightly less than 180 with respect to the armature. It will be seen, therefore, that when the relay is deenergized, any tendency of the armature to move upwardly due, for example, to vibration will cause the end of the latchl to wedge against the riser 15b and will thus prevent further movement of either the latcih or the armature.

.Suiiicient clearance is provided between the end of the latch and the riser 15b so that when the energizing coil 4 is energized by current of either polarity, the latch may be lifted by magnetic attraction away from the riser bei-ore the 'ux is strong enough to lift the armature to its energized position. Interposed between the armature stop and the pole piece is a spacer 16 which acts as a pole piece extension and permits ux to ow toward the latch. A portion of spacer 16 is cutout or tapered to provide clearance for the latch so it will not stick or freeze to the spacer when the relay is energized. Likewise, the core pins 5b are secured to the armature 5 to prevent direct armature contact with the pole piece 2L This prevents the armature from sticking in its energized position.

The armature, the latching means, contact springs, and the armature stop are enclosed within a transparent cover member 1c secured in place by suitable screws 1d and 1f.

One advantage of the latching means embodyingmy invention is that the latch can not normally freeze or stick in any position which would prevent the armature trom releasing when the relay becomes deenergized.

Another advantage of my present invention is` that the armature may be picked up by energy of either polarity whereas an armature that is held down by permanent magnetic ux passing through the armature to the pole pieces will only respond to one polarity of energizatio-n.

The latching means provided herein is more efficient than either hold-down springs or a permanent magnet hold-downmeans for a given relay coil and given applied voltage where it is required that the armature respond to either polarity of energization.

Although I have herein shown and described only one form of relay embodying my invention, it is to be understood that various changes and modiiications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim-is:

l. In a relay, the combination with a pivoted armature movable toward and away `from a pole piece according as the relay isenergized'or deenergized, of a magnetizable latch pivotally attached to the armature in a position to be attracted toward said pole piece when said relay is energized by iiux in a series path including said latch and said armature, and an armature stop cooperating with said latch in the deenergized position of the armature in such manner that upward movement of the armature is restricted except when the latch is attracted due to energization of the relay.

2. In a relay including a frame, a pole piece, an armature pivotally mounted at one end to said frame for movement toward and away from said pole piece between an energized and a deenergized position, a latch pivotally secured to the armature and disposed at an angle with respect to ythe plane of the armature, said latch being energized by iiux in a series path including said latch and said armature, an armature stop provided with an angled step, the free end of said latch resting on said step and abutting a riser of said step to prevent movement of said armature when the relay is deenergized, and a latch stop on said armature for restricting upward movement of said latch.

3. In a relay, a pole piece, an armature pivotally mounted at one end and movable toward and away` from said pole piece to an energized or deenergized position, a latch supporting member secured to the free end of said armature and provided with downwardly extending portions, a pin, a latch of magnetizable material pivotally mounted on a pin supported by the downwardly extending portions ofsaid latch supporting member, said latch being energized by ilux in a series path including said latch and said armature, a nonmagnetizable armature stop secured to said pole piece and having a leg extending beneath the latch supporting member to limit movement of the armature in one direction to a predetermined position when the relay is deenergized, said armature stop also being provided with an angled step including a riser and a tread, the parts being so proportioned that when said armature occupies-its deenergized position one end of said latch will rest on the tread of the step and will be disposed at an angle with respect to said armature, whereby any upward movement of the armature will cause the end of the latch to wedge against the riser and limit the movement unless the latch is irst lifted out of said step, a latch stop which limits upward movement of the latch, and a spacer which acts as an extension of said pole piece through which flux flows to the latch when the relay is energized.

References Cited in the le of this patent- UNITED STATES PATENTS 1,100,134 Jacobson June 16, 1914 l,92l,272 Valkenburg Aug. 8, 1933 1,946,132 Dawe Feb. 6, 1934 

